Generally, removable covers are used for dosing ports through decks of boats that connect with tanks within the boat hulls such as fuel tanks and water tanks. Such covers are also used with aircraft. Fuel tanks of boats and planes present special hazards since diesel fuel is flammable, and gasoline and jet fuel are both flammable and explosive. If a boat is being fueled with gasoline, there is always a danger of a spark occurring in or adjacent to the tank that can initiate an explosion. Accordingly, it is advisable that covers for these ports be removed and replaced carefully with minimal slippage of tools which could result in a spark if a tool strikes a metal object. Frequently, tools for opening covers are misplaced and screwdrivers are used which can slip out of a groove that usually extends between the two holes normally adapted to receive pins projecting from a key.
Normally, covers are attached to a fuel port with a ball chain which is anchored within the port. These chains break rather frequently so that after a cover has been removed, it is no longer secured and can fall overboard. Since there is usually no spare cover aboard, a boater might simply replace the cover with a rag which unfortunately may serve as a wick, thus lifting gasoline vapors out of the fuel tank. These vapors can accumulate in the hull outside of the fuel tank and present an explosion hazard.
In many instances, covers for fuel or water ports are not conveniently accessible in boats, requiring the person opening the port to extend their arms into recessed areas. Moreover, ports are frequently, located in a deck, which requires the person opening the port to kneel or stoop in order to reach the port with a key. Kneeling and stooping can be uncomfortable and on occasion results in injury. Consequently, there is a need to have a marine tool which makes it easier to remove and replace covers. The same general concerns are an issue for the fuel ports of aircraft.